It is well-known in the art that microstrip antenna arrays radiate efficiently as devices on printed circuit boards. These arrays typically consist of microstrip antenna elements, dielectric substrates, and feed and phasing networks, along with other microstrip devices. The lightweight and compact design of microstrip antennas make them suitable for use in airborne and satellite applications.
One type of microstrip antenna is a slot fed antenna. The slot fed antenna typically operates at a single frequency band. If an application requires multiple frequencies, then multiple slot-fed antenna circuits are integrated within an array to perform the required system function.
This integration may cause potential problems with the antenna system. The individual circuits used in combination to radiate multiple signals add unwanted mass to the system. Also, multiple circuits utilize much needed space within a satellite application. Additionally, multiple circuits must be individually joined, or interfaced, which requires more assembly time, thereby adding cost to the antenna system.
It is an object of the present invention to provide an improved slot fed antenna and an improved antenna circuit. It is also an object of the present invention to provide a slot fed antenna which transmits multiple frequency bands.